/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.iotdb.hive;

import org.apache.hadoop.io.MapWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.InputSplit;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.RecordReader;
import org.apache.iotdb.hadoop.tsfile.IReaderSet;
import org.apache.iotdb.hadoop.tsfile.TSFInputSplit;
import org.apache.iotdb.hadoop.tsfile.TSFRecordReader;
import org.apache.iotdb.tsfile.read.TsFileSequenceReader;
import org.apache.iotdb.tsfile.read.common.Field;
import org.apache.iotdb.tsfile.read.common.RowRecord;
import org.apache.iotdb.tsfile.read.query.dataset.QueryDataSet;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import static org.apache.iotdb.hadoop.tsfile.TSFRecordReader.getCurrentValue;

public class TSFHiveRecordReader implements RecordReader<NullWritable, MapWritable>, IReaderSet {

    private static final Logger logger = LoggerFactory.getLogger(TSFHiveRecordReader.class);

    /**
     * all datasets corresponding to one specific split
     */
    private List<QueryDataSet> dataSetList = new ArrayList<>();
    /**
     * List for name of devices. The order corresponds to the order of dataSetList. Means that
     * deviceIdList[i] is the name of device for dataSetList[i].
     */
    private List<String> deviceIdList = new ArrayList<>();
    /**
     * The index of QueryDataSet that is currently processed
     */
    private int currentIndex = 0;

    private boolean isReadDeviceId;
    private boolean isReadTime;
    private TsFileSequenceReader reader;
    private List<String> measurementIds;

    @Override
    public boolean next(NullWritable key, MapWritable value) throws IOException {
        while (currentIndex < dataSetList.size()) {
            if (!dataSetList.get(currentIndex).hasNext()) {
                currentIndex++;
            } else {
                RowRecord rowRecord = dataSetList.get(currentIndex).next();
                List<Field> fields = rowRecord.getFields();
                long timestamp = rowRecord.getTimestamp();

                try {
                    MapWritable res = new MapWritable();
                    getCurrentValue(
                            deviceIdList,
                            currentIndex,
                            timestamp,
                            isReadTime,
                            isReadDeviceId,
                            fields,
                            measurementIds)
                            .forEach((k, v) -> res.put(new Text(k.toString().toLowerCase()), v));
                    value.putAll(res);
                } catch (InterruptedException e) {
                    Thread.currentThread().interrupt();
                    throw new IOException(e.getMessage());
                }

                return true;
            }
        }
        return false;
    }

    @Override
    public NullWritable createKey() {
        return NullWritable.get();
    }

    @Override
    public MapWritable createValue() {
        return new MapWritable();
    }

    @Override
    public long getPos() {
        // can't know
        return 0;
    }

    public TSFHiveRecordReader(InputSplit split, JobConf job) throws IOException {
        if (split instanceof TSFInputSplit) {
            TSFRecordReader.initialize((TSFInputSplit) split, job, this, dataSetList, deviceIdList);
        } else {
            logger.error(
                    "The InputSplit class is not {}, the class is {}",
                    TSFInputSplit.class.getName(),
                    split.getClass().getName());
            throw new InternalError(
                    String.format(
                            "The InputSplit class is not %s, the class is %s",
                            TSFInputSplit.class.getName(), split.getClass().getName()));
        }
    }

    @Override
    public float getProgress() {
        return 0;
    }

    @Override
    public void close() throws IOException {
        dataSetList = null;
        deviceIdList = null;
        reader.close();
    }

    @Override
    public void setReader(TsFileSequenceReader reader) {
        this.reader = reader;
    }

    @Override
    public void setMeasurementIds(List<String> measurementIds) {
        this.measurementIds = measurementIds;
    }

    @Override
    public void setReadDeviceId(boolean isReadDeviceId) {
        this.isReadDeviceId = isReadDeviceId;
    }

    @Override
    public void setReadTime(boolean isReadTime) {
        this.isReadTime = isReadTime;
    }
}
